Ceramic thermal spray coatings are used in various applications according to the properties of the constituent ceramics. For example, aluminum oxide thermal spray coatings are used as protective coatings for various members because aluminum oxide exhibits high electric insulation, abrasion resistance, and corrosion resistance. Yttrium oxide thermal spray coatings are used as protective coatings for members in semiconductor device production apparatuses because yttrium oxide exhibits high plasma erosion resistance (see, for example, patent document 1 and patent document 2).
However, due to the fact that a thermal spray coating is intrinsically porous, a ceramic thermal spray coating may be poor in mechanical, electric, or chemical properties as compared with a sintered bulk ceramic. For example, an aluminum oxide thermal spray coating is poor in electric insulation, abrasion resistance, or corrosion resistance as compared with a sintered bulk aluminum oxide. An yttrium oxide thermal spray coating is poor in plasma erosion resistance as compared with a sintered bulk yttrium oxide.